Grease compositions

ABSTRACT

GREASE COMPOSITIONS ARE PROVIDED COMPRISING A LUBRICATING VEHICLE, A GREASE-FORMING QUANTITY OF A THICKENING AGENT AND A MINOR AMOUNT OF AN IMPROVING AGENT COMPRISING AN ETHYLENE-VINYL ESTER-ORGANIC ACID TERPOLYMER.

3,765,853 GREASE CUMPUSETHUNS Paul Fan, Cherry Hill, and Richard J.Petrueco, Laurel Springs, N..l., assignors to Mobil Oil Corporation NoDrawing. Filed Sept. 23, 197i), Ser. No. 74,849 lint. Cl. 10m 5/20, 5/12US. Cl. 252-36 15 Claims ABSTRACT OF THE DISCLOS JRE Grease compositionsare provided comprising a lubricating vehicle, a grease-forming quantityof a thickening agent and a minor amount of an improving agentcomprising an ethylene-vinyl ester-organic acid terpolyrner.

BACKGROUND OF THE INVENTION (1) Field of the invention This inventionrelates to grease compositions and relates more particularly to greasecompositions having improved resistance to water wash-out and resistanceto softening at high temperature conditions.

(2) Description of the prior art The prior art has, heretofore, proposedthe incorporation of ethylene-vinyl acetate copolymers for improvingwater wash-out resistance of greases. The use of such cpolymers has,however, not been effective in certain greases such as calcium-leadcomplex thickened formulations in which no significant water wash-outresistance was exhibited. Furthermore, it has also been found that suchgreases, as well as other grease formulations, in addition to exhibitingpoor resistance to water wash-out, also tended to soften in hightemperature environments.

SUMMARY OF THE INVENTION In accordane with the present invention, thereare provided grease compositions having improved resistance to waterwash-out and resistance to softening at high temperature conditions,containing, as an improving agent, a minor amount sufi'icient toincorporate the aforementioned resistance, of an ethylene-vinylester-organic acid terpolymer, as more fully hereinafter described.

More specifically the terpolymers of the grease formulations of thepresent invention has a melt index of 0.5 to 200 and contain: (1) atleast 65%, by Weight, of ethylene, (2) at least 5%, by weight, of asecond ethylenically unsaturated monomer which is an ester of the groupcon- I sisting of the vinyl esters of the lower (16 carbon) satu ratedaliphatic carboxylic acids; the alkyl acrylates, the alkylmethacrylates, the dialkyl maleates and the diaikyl fumarates of thelower (16 carbon) aliphatic alcohols; and (3) 0.01 to 3%, by weight, ofa third ethylenically unsaturated monomer of the group consisting ofacrylic, methacrylic, itaconic, maleic and fumaric acids; the anhydridesof itaconic, maleic and furnaric acids; the alkyl hydrogen maleates andthe alkyl hydrogen fumarates; the monoacrylates and monomethacrylates ofglycols; 2-hydroxy-3-aminopropyl allyl ether, allyl glycerol ether,divinyl glycol, 2-dimethylaminoethyl acrylate, Z-dimethylaminoethylmethacrylate and N-vinyl pyrrolidone, The preparation of theabove-described terpolymer improving agents is more fully disclosed inUS. Pat 3,215,657, issued Nov. 2, 1965.

Patented Dec. 12, 1972 A wide variety of thickening agents can be usedin the greases of this invention. Included among the thickening agentsare alkali and alkaline earth metal soaps of fatty acids and fattymaterials having from about 12 to about 30 carbons atoms per molecule.The meals are typified by sodium, lithium, calcium and barium. Fattymaterials are illustrated by stearic acid, hydroxystearic acid, stearin,cottonseed oil acids, oleic acid, palmitic acid, myristic acid andhydrogenated fish oils.

Other thickening agents include salt and salt-soap complexes as: calciumstearate-acetate (Pat. No. 2,197,263); barium stearate-acetate (Pat. No.2,564,561); calcium stearate-caprylate-acetate complexes (Pat. No.2,999,065); calcium caprylate-acetate (Pat. No. 2,999,066); and calciumsalts and soaps of low-, intermediateand high molecular weight acids andof nut oil acids; and aluminum-complexes.

Another group of thickening agents comprise substituted ureas,phthalocyanines, indanthrene, pigments such as perylimides,pyromellitdiimides, ammeline, and carbon black.

Other thickening gelling agents employed in the new grease compositionsare essentially hydrophobic clays. Such thickening agents can beprepared from clays which are initially hydrophilic in character, butwhich have been converted into a hydrophobic condition by theintroduction of long chain hydrocarbon radicals into the surface of theclay particles, prior to their use as a component of a greasecomposition, as, for example, by being subjected to a preliminarytreatment with an organic cationic surface active agent, such as anonium compound. Typical onium compounds are tetra alkyl ammoniumchlorides, such as dimethyl dioctadecyl ammonium chloride, dimethyldibenzyl ammonium chloride and mixtures thereof. This method ofconversion, being well known to those skilled in the art, is believed torequire no further discussion, and does not form a part of the presentinvention. More specifically, the clays which are useful as startingmaterials in forming the thickening agents to be employed in the greasecompositions, can comprise the naturally occurring chemically unmodifiedclays. These clays are crystalline complex silicates, the exactcomposition of which is not subject to precise description, since theyvary widely from one natural source to another. These clays can bedescribed as complex inorganic silicates such as aluminum silicates,magnesium silicates, barium silicates, and the like, containing, inaddition to the silicate lattice, varying amounts of cation-exchangeablegroups such as sodium. Hydrophilic clays which are particularly usefulfor conversion to desired thickening agents include montmorilloniteclays, such as bentonite, attapulgite, hectorite, illite, saponite,sepiolite, biotite, vermiculite, zeolite, clays and the like. Preferredthickening agents are calcium leadacetate complexes employed in greaseformulations as described in US. Pat. 2,898,297, issued Aug. 4, 1959.Such thickening agents comprise a mixture of (A) alkaline earth metaisoaps and salts therewith, the alkaline earth metals being selected fromthe group consisting of calcium and a mixture (B) of calcium and barium,not more than about 15% of barium on a chemical equivalent basis beingassociated in said mixture (B) with calcium in said soaps and salts, themixture (A) of said soaps and salts being present in a grease-formingquantity, and the metal salts of said mixture (A) being salts of a lowmolecular weight unsubstituted saturated monocarboxylic acid (I) havingfrom 1 to 6 carbon atoms per molecule, and the metal soaps of saidmixture (A) being soaps of different acids with said acid (I) as shownin the following tabulation:

said acid (II) being selected from unsubstituted,monohydroxy--substituted and methyl-substituted saturated aliphaticmonocarboxylic acids, and acids (III) being selected from unsubstitutedand monohydroxy-substituted saturated aliphatic monocarboxylic acids andmonounsaturated aliphatic monocarboxylic acids; and said oil acids beingnut oil acids comprising mixtures of acids containing from about 8 to 18carbon atoms per molecule and predominating in O -C acids; and fromabout 0.5 to about by weight (expressed as PbO) of at least one leadcompound of at least one of said acids (1) through (IV).

Oils used in the greases of this invention can be mineral or syntheticoils of lubricating viscosity. Suitable mineral oils have a viscosity(SUS) of at least 40 seconds at 100 F., and particularly those withinthe range of about 60 seconds to about 6000 seconds at 100 F.

Synthetic vehicles can be used, instead of mineral oils, or incombination therewith. Typical synthetic vehicles are: polypropylene,polypropylene glycol, trimethylol propane esters, neopentyl andpentaerythritol esters, di-(2- ethyl hexyl) sebacate, di(2-ethyl hexyl)adipate, dibutyl phthalate, polyethylene glycol di(2-ethyl hexoate),fluorocarbons perfiuoro-alkyl-polyethers, silicate esters, silanes,esters of phosphorus-containing acids, liquid ureas, ferrocenederivatives, hydrogenated mineral oils, chain type polyphenyls,siloxanes, and silicones (polysiloxanes) fluorosilicones,alkyl-substituted diphenyl ethers typified by a butyl-substitutedbis-(p-phenoxy phenyl) ether, and phenoxy phenyl ethers.

Other hydrocarbon oils include synthetic hydrocarbon polymers havingimproved viscosity indices, which polymers are prepared by polymerizingan olefin, or mixture of olefins, having from 5 to 18 carbon atoms permolecule in the presence of an aliphatic halide and a Ziegler-typecatalyst.

It is to be understood, however, that the compositions contemplatedherein can also contain other characterizing materials. For example,antioxidants such as phenyl alphanaphthylamine (PAN), corrosioninhibitors, extreme pressure agents, viscosity index agents, and fillerscan be used. Among such materials are colloidal silica, calcium acetate,calcium carbonate and molybdenum disulfide. Such characterizingmaterials do not detract from the lubricating value of the compositionsof this invention, nor do they detract from the beneficial character ofthe terpolymers; rather, the characterizing materials serve to imparttheir customary properties to the particular compositions in which theyare incorporated.

The greases of this invention can be prepared in accordance withconventional grease manufacturing procedures, as by any mixing techniquewherein solid particles are wetted by a fluid. Typical equipment forsuch use includes a colloid mill, 3-roll ink mill, Manton-Gaulinhomogenizer and the like.

With reference to the terpolymer improving agents of the presentinvention, preferred terpolymers contain from about 20 to about byweight, of the aforementioned group (2) component, i.e. the secondethylenically unsaturated monomer component; and from about 0.1 to about1%, by weight, of the aforementioned group (3) component, i.e. the thirdethylenically unsaturated monomer component. Representative preferredterpolymer comprise, in addition to ethylene, from about 20 to about 30%by weight, vinyl acetate and from about 0.1 to about 1%, by g y c acifrom, about 20 to about 30%, y

weight, vinyl acetate and from about 0.1 to about 1%, by weight,methacrylic acid; from about 20 to about 30%, by weight, ethyl acrylateand from about 0.1 to about 1%, by weight, acrylic acid; from about 20to about 30%, by weight, ethyl acrylate and from about 0.1 to about 1%,by weight, methacrylic acid; from about 20 to about 30%, by weight,methyl methacrylate and from about 0.1 to about 1%, by weight acrylicacid; and from about 20 to about 30%, by weight, methyl methacrylate andfrom about 0.1 to about 1%, by Weight methacrylic acid.

Insofar as the quantity of terpolymer improving agent is concerned, thelatter, as previously indicated, is employed in a minor amountsufiicient to incorporate in the grease formulation the desiredresistance to water washout and resistance to softening at hightemperature conditions. Particularly preferred are greases in which theterpolymer is present in an amount of at least about 0.01%, by weight,and for most purposes, the presence of the terpolymer in an amount fromabout 0.1 to about 5%, by weight, produces highly satisfactory improvedgrease compositions.

DESCRIPTION OF SPECIFIC EMBODIMENTS In order to demonstrate theimprovement of water washout resistance and resistance to softening atelevated temperatures, employing the above-described terpolymers, atypical calcium-lead complex grease was prepared comprising, by weight,16% thickener, vehicle and 4% additives.

The thickener was formed by the reaction of a slight stoichiometricexcess of metal base consisting of 4.5 parts of lime to 1 part litharge,with fatty acids comprising 27.5%, by weight, of a low molecular weightacid, viz acetic acid; 58%, by weight, of an intermediate molecularweight fatty acid, viz caprylic acid; and 14.5%, by Weight of highmolecular Weight acids, viz coconut oil acids (C C The vehicle compriseda naphthenic solventrefined mineral oil stock of a viscosity of 800 SUSat F. and 70 SUS at 210 F. The additives comprised 2%, by weight, ofchlorinated wax as an extreme pressure agent; 0.8%, by weight, ofantioxidants, viz hindered phenol and aromatic amine; and 1.2%, byweight, of corrosion inhibitors.

As is shown in the examples of the following Table I, varying quantitiesof a typical representative terpolymer were incorporated in theabove-prepared grease for evaluation. This terpolymer comprised anethylene-vinyl acetate-methacrylic acid terpolymer, having a melt indexof 13 and containing 27.5 by weight, vinyl acetate, 0.7%, by weight,methacrylic acid, and 71.8%, by weight, ethylene.

The respective grease formulations, containing the indicated amounts ofthe above-prepared terpolymer, by weight, were subjected to the standardWater Wash-out Test, ASTM D1264, employing a wider annular shield tofacilitate passage of water into the grease-packed bearing.

TABLE I.INFLUENCE OF TERPOLYMER ON WASH OU'I ly effective in impartingresistance to water wash-out of grease compositions.

As is shown in the examples of the following Table II, varyingquantities of the above-described representative terpolymer wereincorporated in the above-described grease for evaluation with respectto resistance to softening effect at elevated temperatures.

10. A grease composition as defined in claim 1 wherein the vehiclecomprises a mineral lubricating oil.

TABLE II.INFLUENCE OF TERPOLYMER ON SOFTENING EFFECT Wheel bearing leakae test Softening efiect (percent) AS'IM 1263 Consistency modified (260ASTM D217 150 200 250 320 F.l g.), Ex. Grease (UW/GOW) 1 F. F. F. F.leakage (g.).

1 Base grease 301/318 21 3 1 50 12. 1 2 Base grease plus 0.3%terpolymer. 256/286 13 20 33 40 4. 6

1 UW/GOW: Unworked/GO strokes worked. 2 Too soft for penetration to bemeasured.

As will be apparent from the examples of the foregoing 15 11. A greasecomposition as defined in claim 1 where- Table II, the terpolymers ofthe present invention are highly effective in imparting resistance ofthe grease to softening at elevated temperatures.

While this invention has been described with reference to preferredcompositions and components therefor, it will be understood, by thoseskilled in the art, that departures from the preferred embodiments canbe effectively made and are within the scope of the specification.

We claim:

1. A grease composition comprising a lubricating vehicle, agrease-forming quantity of a thickening agent and a minor effectiveamount of an improving agent comprising a terpolymer having a melt indexof 0.5 to 200 and containing: (1) at least 65%, by Weight, of ethylene,(2) at least 5%, by weight, of a second ethylenically unsaturatedmonomer which is an ester of the group consisting of: the vinyl estersof saturated aliphatic carboxylic acids having 1-6 carbons; the alkylacrylates, the alkyl methacrylates, the dialkyl maleates and the dialkylfumarates of aliphatic alcohols having 16 carbons; and (3) 0.01 to 3.0%,by weight, of a third ethylenically unsaturated monomer of the groupconsisting of: acrylic, methacrylic, itaconic, maleic and fumaric acids;the anhydrides of itaconic, maleic and fumaric acids; the alkyl hydrogenmaleates and the alkyl hydrogen fumarates; the monoacrylates andmonomethacrylates of glycols; Z-hydroxy- 3-aminopropyl allyl ether,allyl glycerol ether, divinyl glycol, Z-dimethylaminomethyl acrylate,2-dimethylaminoethyl methacrylate and N-vinyl pyrrolidone.

2. A grease composition as defined in claim 1 wherein the terpolymercontains from about 20 to about 30%, by weight, of the group (2)component.

3. A grease composition as defined in claim 1 wherein the terpolymercontains from about 20 to about 30%, by Weight, of the group (2)component and from about 0.1 to about 1%, by weight, of the group (3)monomer component.

4. A grease composition as defined in claim 1 wherein the terpolymercontains from about 20 to about 30%, by weight, vinyl acetate and fromabout 0.1 to about 1%, by weight, acrylic acid.

5. A grease composition as defined in claim 1 wherein the terpolymercontains from about 20 to about 30%, by weight, vinyl acetate and fromabout 0.1 to about 1%, by weight, methacrylic acid.

6. A grease composition as defined in claim 1 wherein the terpolymercontains from about 20 to about 30%, by weight, ethyl acrylate and fromabout 0.1 to about 1%, by weight, acrylic acid.

7. A grease composition as defined in claim 1 wherein the terpolymercontains from about 20 to about 30%, by weight, ethyl acrylate and fromabout 0.1 to about 1%, by weight, methacrylic acid.

8. A grease composition as defined in claim 1 wherein the terpolymercontains from about 20 to about 30%, by weight, methyl methacrylate andfrom about 0.1 to about 1%, by weight, acrylic acid.

9. A grease composition as defined in claim 1 wherein the terpolymercontains from about 20 to about 30%, by weight, methyl methacrylate andfrom about 0.1 to about 1%, by weight, methacrylic acid.

in the vehicle comprises a synthetic lubricating oil.

12. A grease composition as defined in claim 1 Wherein said terpolymeris present in an amount of at least 0.01%, by weight.

13. A grease composition as defined in claim 1 wherein said terpolymeris present in an amount from about 0.1 to about 5%, by weight.

14. A grease composition as defined in claim I wherein the thickeningagent comprises a mixture of (A) alkaline earth metal soaps and saltstherewith, the alkaline earth metals being selected from the groupconsisting of calcium and a mixture (B) of calcium and barium, not morethan about 15% of barium on a chemical equivalent basis being associatedin said mixture (B) with calcium in said soaps and salts, the mixture(A) of said soaps and salts being present in a grease-forming quantity,and the metal salts of said mixture (A) being salts of a low molecularweight unsubstituted saturated monocarboxylic acid (I) having from 1 to6 carbon atoms per molecule, and the metal soaps of said mixture (A)being soaps of different acids with said acid (I) as shown in thefollowing tabulation:

l At least 13.

1 said acid (II) being selected from unsubstituted,monohydroxy-substituted and methyl-substituted saturated aliphaticmonocarboxylic acids, said acids (III) being selected from unsubstitutedand monohydroxy-substituted saturated aliphatic monocarboxylic acids andmonounsaturated aliphatic monocarboxylic acids; and said oil acids beingnut oil acids comprising mixtures of acids containing from about 8 to 18carbon atoms per molecule and predominating in C -C acids; and fromabout 0.5 to about 5%, by weight, expressed as PhD, of at least one leadcompound of at least one of said acids (I) through (IV).

15. A grease composition as defined in claim 1 wherein said terpolymerhas a melt index of about 13 and contains about 71.8%, by weight,ethylene, about 27.5%, by weight, vinyl acetate and about 0.7%, byweight, methacrylic acid.

References Cited UNITED STATES PATENTS 3,455,826 7/1969 Feicher et al.252-56 3,324,034 6/1967 Merz et al. 252-56 3,354,086 11/1967 Panzer etal. 252-515 R 3,621,004 11/1971 Eckert 252-56 R DANIEL E. WYMAN, PrimrayExaminer I. VAUGHN, Assistant Examiner US. Cl. X.R.

252-515 R, 51.5 A, 56 R Po-ww UNITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION Patent No. 5, 5 v Dated December 97 Inventor) PAUL FAU andRICHARD J. PETRUCCO It. is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Column l, Line #6 "has" should read "have". Column 2, Line 5 meals"should reed --meta ls-. Column 3, Line 13 "and" should read --salid--.Column 3, Line '72 terpoly'mer" should read --terpolymers--. Column 5,Line #3 "dimethylaminomethyl" ehould read --dimethylaminoethyl--. v

Signed and sealed this 22nd day of May l973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents

